The quip prompted a huge reaction on Twitter from fans afterwards.
He spent a lot of time urging viewers to take part in social distancing and calling those who are ignoring this advice "morons."
The host later lightened the mood and said to Phillip Schofield : "And Phil for you, weird right? You've come out and everyone has gone in."
This was referring to the This Morning hosts recent revelation that despite his long marriage to a women, he is in fact gay.
The This Morning host did not seem at all phased by Pier's gentle teasing. One Twitter user said: "Schofe seems to find it funny! Bit savage but comedy gold!"
Many viewers found Pier's comment hilarious and flocked to Twitter to share their amusement.
One said: "Omg @piersmorgan that comment to @Schofe was the funniest thing I've ever heard"
Another agreed: "Just made my day what you said to Phillip Schofield"Phillip Schofield came out as gay last month, and recently revealed he was taken to "the darkest of places” while keeping his sexuality hidden from the world.
The 57 year old star came out to his fans on social media in a statement on Snapchat and Instagram.
He wrote: "With the strength and support of my wife and my daughters, I have been coming to the terms with the fact that I am gay."
He continued: "This is something that has caused many heart-breaking conversations at home. I have been married to Steph for nearly 27 years, and we have two beautiful grown-up daughters, Molly and Ruby.
"My family have held me so close: they have tried to cheer me up, to smother me with kindness and love, despite their own confusion.
"Yet I still can't sleep and there have been some very dark moments."
He followed the news with an interview on This Morning with his co star Holly Willoughby.
Phil admitted that he'd reached the point where he didn't like himself because he wasn't being honest.
"I got to the stage where I thought we sit here, every day, and some amazingly brave person is sitting over there and I'm thinking, 'I have to be that person'.
At the end of the interview, Friday's usual presenters Ruth Langsford and Eamonn Holmes came on-set and embraced Phil.
Good Morning Britain airs on ITV, weekdays at 6am.